That doesn't really do what the original poster asked for tho' does it? Ascii characters are those with a character code between 0 and 128. Your code only checks for character codes between 33 and 126 (plus a few whitespace characters).

To match _all_ non-ascii characters you really need something like:

/[^\x00-\x7f]/
[download]

^ = exclude
!-~ = all characters between ! and ~
\s = or spaces
g = search globally

As davorg has pointed out, mine is a rough regex but I use it often to find non-English characters in my xml files, as it not only works embedded in a perl script but also with editors that use perl-based regex's such as my favourite Unired.